Mark Hammer, 69, who acted at Arena Stage and taught drama at Catholic University and whose work spanned theater, film and television, died Feb. 15 at Christ Hospital in Jersey City. He had complications of renal failure, diabetes and sepsis.

Mr. Hammer, a talented character actor of expansive range, performed at Arena Stage from 1973 to 1991 and taught scores of students at Catholic from 1966 to 1989. His theater career took him to stages throughout the United States and the world. He appeared on and off Broadway as King Creon opposite Diana Riggs in "Medea" and as the aging Father Lux in the 2003 New York premiere of the LAByrinth Theater Company's "Our Lady of 121st Street."

He also specialized in Shakespeare and appeared numerous times in New York Shakespeare Festival productions in Central Park. He narrated recordings of more than 60 classic and contemporary novels, including works by William Faulkner, Elmore Leonard and James Lee Burke.

In 70 productions over 18 years with Arena Stage, Mr. Hammer played such roles as Sheridan Whiteside in "The Man Who Came to Dinner," Captain Shotover in George Bernard Shaw's "Heartbreak House," Pozzo in Samuel Beckett's "Waiting for Godot" and prosecutor Tom Norman in Emily Mann's "Execution of Justice."

Guy Bergquist, Arena Stage facility project director, was the producer of the theater when Mr. Hammer was a company member. "He was a talented actor, a key leader of the ensemble group and great educator of the craft of acting," Bergquist said. "He was as genuinely warm and engaging off-stage as the characters he portrayed on."

Mr. Hammer was twice nominated for the Helen Hayes Award, for Joshua/Cathy in "Cloud Nine" and Old Ekdal in Lucien Pintilie's staging of "The Wild Duck." He traveled with Arena Stage productions to Russia with "Inherit the Wind" and "Our Town"; China with "You Can't Take It with You" and "After the Fall"; and Israel with "The Crucible."

In 1980, Mr. Hammer took on his first leading role at Arena Stage when he played tyrannical Sheridan Whiteside. Washington Post reviewer James Lardner praised Mr. Hammer for mastering his character.

"At first the quips roll too effortfully off Hammer's tongue, and the wit sounds like store-bought goods," Lardner wrote. "But as the play gets cooking, Hammer becomes steadily more spontaneous and energetic; and when he fumes, snarls, grunts, wheezes with displeasure, or blows Machiavellian smoke rings in the air -- as he will do from time to time -- he is a roly-poly, despotic delight."

Mr. Hammer once described acting as "the spirit's response to the body's mortality -- live enough lives within the span of the one life endows, and you've beaten the game." He said theater was "one of humanity's communal responses to its awareness of mortality."

"Theater is, among other things, an extraordinary means of stationary travel," he wrote, "and as a tour guide to inner worlds of unique human identities, I am committed, by purpose as well as preference, to the pursuit of 'the undiscovered self.' Each role I undertake must introduce me and my audience to a stranger -- a self none of us has met before."

Mr. Hammer was born April 28, 1937, in San Jose and graduated from Stanford University in 1959. He received a master's degree in fine arts in theater from Catholic University in 1962 and was enrolled for a year in the doctoral program in theater at Stanford. At Stanford, he edited a humor magazine, the Stanford Chapparal.

For more than four decades, Mr. Hammer taught acting, improvisation, comedy technique and dramatic literature.